1. Technical Field
The present invention relates to disk drive apparatuses that are employed as data storage means for computers.
2. Description of the Related Art
The most commonly used data storage means for computers are hard-disk drives (HDDs) having structures in which one or more magnetic disks are disposed coaxially and driven by a spindle motor. Data reading and writing are done by magnetic heads provided in opposition to the magnetic disks. The magnetic heads are driven by an actuator, generally a voice coil motor (hereinafter referred to as a VCM). The magnetic disks, the magnetic heads, and the actuator are stored in a housing called an enclosure case.
Two major performance concerns regarding an HDD are storage capacity per magnetic disk and read/write speed. Regarding the latter, data reading and writing speeds can be increased by shortening the seek time required to get a magnetic head to the required track on a magnetic disk. Because the magnetic head is driven by the VCM, as described above, it is possible to make the seek speed faster by enhancing the performance of the VCM. To enhance the VCM performance, the magnetic characteristic of the permanent magnets constituting the VCM can be made stronger, or the thickness can be adjusted to increase a magnetic field that is applied across the voice coil. There is a limit, however, to the extent to which the magnetic characteristic of the permanent magnets can be enhanced due to the practical limitations on increasing the thickness of the permanent magnet.
The speed of reading out or writing data can be enhanced by making the rotational speed of a magnetic disk faster. However, if the rotational speed of a magnetic disk is made faster, flutter of the magnetic disk will be increased. xe2x80x9cFlutterxe2x80x9d refers to a phenomenon in which a magnetic head oscillates in the radial direction of a magnetic disk because of a flow air created by the high rotational speed of the magnetic disk. If flutter occurs, the positional relationship between the magnetic head and the magnetic disk may be compromised. Increased flutter may therefore have an adverse effect on accuracy of data reading and writing (e.g. data may be written to or read from the wrong track). As storage densities increase, the negative effects of flutter are magnified.
The rotational speed of a 3.5-in magnetic disk has conventionally been 7200 rpm, with rotational speeds of 10000 rpm for more currently being adopted. Flutter becomes more pronounced as the flow velocity (flow velocity) of air occurring between magnetic disks increases. The velocity (flow velocity) of the flow of air occurring between magnetic disks increases as the rotational speed of a magnetic disk increases. Therefore, if the rotational speed of magnetic disks in an HDD is increased, the problem of erroneous data reads and writes due to flutter also increases.
In addition to inducing data reading and writing errors, flutter is an important consideration in the manufacturing and assembly of HDDs. In most cases, a plurality of magnetic disks are mounted in the HDD. If there is a difference in the flutter characteristic between magnetic disks mounted within a single HDD, it is necessary to design in compensation for such flutter disparities.
From the foregoing, it can be appreciated that a need exists for a disk drive apparatus which, in a high-speed HDD, is capable of reducing the velocity of a flow of air occurring near magnetic disks during rotation of the magnetic disks so that flutter occurrence can be suppressed. It would further be useful to provide a disk drive apparatus which, in a HDD with a plurality of magnetic disks, is capable of equalizing the velocities of the flows of air between the magnetic disks.
A disk drive apparatus and method applicable therein for reducing disk flutter and the negative effects thereof are disclosed herein. The apparatus of the present invention includes a hard disk drive unit including a motor that rotatably drives multiple disk data storage media. The hard disk drive unit further includes a disk assembly in which the disk storage media are disposed coaxially in sequence with predetermined spaces from the motor, wherein a space between axially centered disk storage media within the multiple disk storage media is set greater than the other spaces between disk storage media.